Fluxes of Fast and Epithermal Neutrons from Lunar Prospector: Evidence for Water Ice at the Lunar Poles by W. C. Feldman, S. Maurice, A. B. Binder, B. L. Barraclough, R. C. Elphic, and D. J. Lawrence Science Volume 281(5382):1496-1500 September 4, 1998 Published by AAAS

Figure 1 Simulated neutron lethargy-energy spectra for a FAN regolith containing various weight percent admixtures of H2O (w). Simulated neutron lethargy-energy spectra for a FAN regolith containing various weight percent admixtures of H2O (w). These spectra were generated with the ONEDANT part of the DANTSYS code system (27) as discussed in (16). From top to bottom, the spectra correspond to mass fractions of H2O (w) of 0, 0.01, 0.1, 1, 3, 10, 30, and 100%, respectively. R, altitude of spacecraft. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 2 Simulated epithermal and fast-neutron counting rates as a function of mass fraction of H2O (w), added to a FAN regolith. Simulated epithermal and fast-neutron counting rates as a function of mass fraction of H2O (w), added to a FAN regolith. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 3 Simulated epithermal and fast-neutron counting rates for a desiccated FAN layer of varying thickness d that overlays a thick, circular deposit of water ice having a radius of 24.3 km, which is surrounded by a desiccated FAN regolith. Simulated epithermal and fast-neutron counting rates for a desiccated FAN layer of varying thickness d that overlays a thick, circular deposit of water ice having a radius of 24.3 km, which is surrounded by a desiccated FAN regolith. Here and throughout this study, a density of 2 g cm−3 is assumed. Also, inf is an effectively infinite depth. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 4 Histograms of counts per areal pixel of thermal, epithermal, and fast-neutron counting rates. Histograms of counts per areal pixel of thermal, epithermal, and fast-neutron counting rates. The histogram labeled “epithermal*” is constructed by subtracting 6.8% of the thermal histogram from the epithermal histogram. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 5 A full-moon map of the epithermal* counting rates. A full-moon map of the epithermal* counting rates. Both globes are tilted by 45° in latitude with the nearside and North Pole at the left and the farside and South Pole at the right. The scale given in the middle corresponds to the counts registered by the Cd-covered 3He gas proportional counter in 32 s. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 6 Averages and standard deviations of all epithermal Figure 6 Averages and standard deviations of all epithermal* counts for all equal area pixels in Fig. 5 within successive 2° wide latitude bins that are bounded in azimuthal angle by planes that are parallel to the lunar polar axis and separated by 2° in longitude at the equator (EQ). Averages and standard deviations of all epithermal* counts for all equal area pixels in Fig. 5 within successive 2° wide latitude bins that are bounded in azimuthal angle by planes that are parallel to the lunar polar axis and separated by 2° in longitude at the equator (EQ). W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 7 Averages and standard deviations of all fast-neutron counts for all equal area pixels in figure 3 of (22) within successive 2° wide latitude bins that are bounded in azimuthal angle by planes that are parallel to the lunar polar axis and separated by 2° in longitude at the equator. Averages and standard deviations of all fast-neutron counts for all equal area pixels in figure 3 of (22) within successive 2° wide latitude bins that are bounded in azimuthal angle by planes that are parallel to the lunar polar axis and separated by 2° in longitude at the equator. W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS

Figure 8 Overlay of epithermal Figure 8 Overlay of epithermal* counting rates in each 2° by 2° equal area pixel poleward of ±70° with surface relief maps of the lunar poles (28). Overlay of epithermal* counting rates in each 2° by 2° equal area pixel poleward of ±70° with surface relief maps of the lunar poles (28). W. C. Feldman et al. Science 1998;281:1496-1500 Published by AAAS